Diphthongs (i dittonghi) are two vowels fused to emit a single sound. A diphthong is formed when an unstressed i or u combines
with another vowel (a, e, o) or when the two vowels combine with each other, in which case either the i or u may remain unstressed.
In diphthongs, unstressed i and u become semivowels approximating in sound the English consonants y and w, respectively.

Diphthong examples:

Italian English
ieri yesterday
buono good
fiore flower
chiuso closed
invidia envy
più more


Tripthongs also exist. These are sequences of three vowels with a single sound, usually a diphthong followed by an unstressed i.

Italian English
tuoi yours
miei mine
buoi oxen
pigliai I took


Italian has numerous words that contain sequences of vowels. The following words are not triphthongs (which are infrequent), but sequences of a vowel and a diphthong.

Italian English
noia boredom
febbraio February
baia bay
fioraio florist


Each of the words below has a sequence of two diphthongs:

Italian English
ghiaia gravel
muoio I die
acquaio sink
gioiello jewel